The present invention relates to an optical disk capable of high-density recording, reproducing or erasing of high-quality information, and to a method of high-density recording, reproducing or erasing of high-quality information on the optical disk.
There are commercially available "Optical Video Disks" in which video signals are reproduced by way of focusing a laser beam on the optical disk. An optical disk of 30 cm in diameter with a record of frequency modulated television signals at a track pitch of 1.67 .mu.m has a duration of 30 minutes at a turning speed of 1800 RPM for reproduction of the recorded signals on each side. A method has been developed for recording, reproducing or erasing signals in the same way as for video tape by the provision of a thin film of recording material (e.g., tellurium sub-oxide film) on the surface of the optical disk, and it is expected that this will enable expansion to a "Recording/Reproduction Video Disk". Moreover, due to its non-contact operation, which brings semi-permanent service life and high-speed access faster than a VTR (VCR), extensive applications in computer peripheral devices such as "Data Files" are expected.
In the present state of the art, video disks can reproduce higher quality pictures than household VTRs. A new method is being researched which records a video signal on a video tape through a process of digitization and band compression, and digitization of household VTRs recording will be seen in the not too distant future. On this account, it is desired to develop a method of recording, reproducing or erasing high-quality information such as digital video signals on a real-time basis on an optical disk.
It is therefore an object of the present invention to provide a method of recording, reproducing or erasing high-quality information on a real-time basis on an optical disk which is provided with grooves each having a V-shaped cross section in the radial direction of the disk so as to form a pair of information tracks on adjoining slants where discrete pieces of high-quality information are recorded divisionally and reproduced respectively on a real-time basis.